#include <bitset>
#include <vector>
static void Day3A_()
{
    std::ifstream infile("3.txt");
    std::bitset<12> currBitset;
    std::vector<int> binaryCount(12);
    while (infile >> currBitset)
    {
        for (unsigned i = 0; i < currBitset.size(); ++i)
        {
            currBitset.test(i) ? binaryCount[i]++ : binaryCount[i]--;
        }
    }

    std::bitset<12> gamma;
    for (unsigned i = 0; i < binaryCount.size(); ++i)
    {
        gamma.set(i, binaryCount[i] GT 0);
    }
    auto epsilon = ~gamma;

    std::cout << "3A:" << gamma.to_ulong() * epsilon.to_ulong() << "\n";
}

using Bitset = std::bitset<12>;
bool MajoritySet_(int index, const std::vector<Bitset>& list)
{
    int count = 0;
    for (const auto& currBitset : list)
    {
        currBitset.test(index) ? count++ : count--;
    }
    return count GE 0;
}
#include <functional>
using ComparisonFunc = std::function<bool(bool, bool)>;
int FilteredValue_(std::vector<Bitset> list, //copied list since it is modified. HOWEVER, could use std::partition instead of erase_if
    const ComparisonFunc& func)
{
    for (unsigned index = 11; list.size() GT 1 AND index GE 0; --index)
    {
        bool isSet = MajoritySet_(index, list);
        std::erase_if(list, [&](const Bitset& bit) {return func(bit.test(index), isSet); });
    }
    _ASSERT(list.size() EQ 1);
    return list.front().to_ulong();
}

static void Day3B_()
{
    /*
    In string form:
    100000101101
    ^          ^
    11th       0th exponent

    In bitset,
    101101000001
    ^          ^
    0th        11th exponent
    */
    std::vector<Bitset> list;
    std::ifstream infile("3.txt");
    Bitset currBitset;
    while (infile >> currBitset)
    {
        list.push_back(currBitset);
    }
    auto first = FilteredValue_(list, [](const bool b1, const bool b2) {return b1 NE b2; }); //Erase things NOT matching majority
    auto second = FilteredValue_(list, [](const bool b1, const bool b2) {return b1 EQ b2; }); //Erase things matching majority.
    std::cout << "3B:" << first * second << "\n";
}